The primary mechanism for the clearance of foreign particles from the lung is the mucociliary transport system which begins in the terminal bronchioles and extends through the trachea. The objective of the proposed research is to describe in detail the movement of cilia on the ciliated epithelium of the mucosa and the relationship of their movement to the movement of mucus and particles. This will be done in isolated trachea and bronchioles and in whole lung preparations of the rat, and in the frog oropharynx in situ. Cilia on bivalve gill and palps will be studied for comparison. Scanning electron micrographs of ciliated surfaces will be taken after rapid fixation to preserve the metachronal wave.